Association between the serum folate levels and tea consumption during pregnancy

Folate is a vital nutrient during pregnancy for the prevention of neural tube defects, intrauterine fetal growth restriction and preeclampsia. Circulating folate levels might be negatively affected by ()-epigallocatechin gallate, which is a tea catechin found in green tea and oolong tea. The aim of this study was to determine whether consumption of green tea or oolong tea was associated with circulating folate levels among pregnant women in Japan. Two hundred and fifty-four healthy women with a singleton pregnancy (age: 30.4 ± 4.7, gestational age: 27.5 ± 9.6 weeks) were recruited from a prenatal clinic in metropolitan Tokyo, Japan. The serum folate levels were measured. Nutrient intake was assessed using a self-administered diet history questionnaire. Information on lifestyle variables was obtained from the questionnaire. The high consumption of green tea or oolong tea was defined as consumption more than 57.3 mL per 1,000 kcal, which is the 75th percentile of participants. The serum folate levels of the participants with high consumption of green tea or oolong tea was significantly lower than those of others (p = 0.027). A multiple regression analysis revealed the high consumption of green tea or oolong tea to be associated with a low serum folate level during pregnancy, after adjusting for confounding variables including dietary folate intake and use of folic acid supplements or multivitamins (β = -0.131, p = 0.016). The association between folate and the consumption of green tea or oolong tea may be useful to clarify the mechanism which links adverse perinatal outcomes and tea consumption.